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October 18, 2007

Experts fear greenhouse gas cuts may be too little, too late

Greenhouse gas reduction targets, set by Prime Minister Stephen Harper and other world leaders are not nearly tough enough to prevent a planetary meltdown, a leading Canadian climate research team reports.

It says global emissions need to be slashed by 90 per by 2050 to avoid a two-degree Celsius rise in the global temperature - a threshold that scientists fear could trigger melting of the Greenland ice sheet and a seven-metre rise in sea level.

Even with such a huge cut in emissions, future generations will still have to extract carbon monoxide out of the air because the gas persists in the atmosphere for so long, the team reports in the Geophysical Research Letters this week.

"Our results suggest that if a 2.0-degree C warming is to be avoided, direct CO2 capture from the air, together with subsequent sequestration would eventually have to be introduced in addition to sustained 90 per cent global carbon emissions reductions by 2050," the University of Victoria team concludes.

The group's experiments indicate many emission reduction targets - which vary widely depending on the government proposing them - are "inconsistent" with the stated aims of the politicians, says lead author Andrew Weaver.

"They're saying: 'We don't want to have two-degree warming, so let's aim for a 40 to 50 per cent cut in emissions'," says Weaver. "What's we're saying is: 'If you want to avoid two-degree warming, then you need to get to 90 per cent cuts by 2050.' "

California and Germany aim to slash their emissions by 80 per cent from 1990 levels by 2050; leaders of several G8 countries have proposed cutting global emissions to 50 per cent below 1990 levels by 2050; and the Harper government wants to cut Canada's current emissions by 60 to 70 per cent by 2050.

"In Canada, we have a history of just making numbers up," says Weaver, who sees little scientific rationale for the targets set by either the former Liberal government or the current Conservative one.

"Maybe they have a Ouija board or something, and they all sit around in a seance," Weaver said in an interview. "There is no rhyme or reason to it. "

The current target set by the Conservatives is "nowhere near enough," says Weaver, stressing the need for the Canada and other countries to wean themselves off fossil fuels to curb carbon emissions from cars, factories and power plants that continue to soar globally.

While two-degree warming globally does not sound like much, many experts believe it will be enough to trigger mass species extinctions and accelerated melting of polar ice sheets. Rajendra Pachauri, head of the UN climate panel, said recently that some scientists are now questioning if the two-degree benchmark is safe enough.

"People are actually questioning if the two-degrees centigrade benchmark that has been set is safe enough," Pachauri, head of the

There are also indications the climate is changing faster than expected. The remarkable loss of sea ice in the Arctic this summer, which scientists and government officials have described as "stunning," has prompted leading ice researchers to say the Arctic may have already passed the tipping point and the summer ice could be gone by 2030.

Weaver's team is one of the few in the world that has computer models with the power and sophistication to assess the long-term impact of different emission reductions.

In a series of nine experiments, Weaver's team found less than 60 per cent global emissions reduction by 2050 breaks the two-degree threshold warming this century. And even when total global emissions are stabilized at 90 per cent below present levels by 2050, the two-degree threshold is broken in centuries ahead because of the way carbon lingers in the atmosphere. While two degrees could trigger melting of the massive Greenland ice sheet, scientists say it would actually take centuries to melt all the ice and raise sea levels seven metres.

In a related study, which was presented an a conference earlier this year and is published this week, Weaver and his colleagues found burning all known reserves of fossil fuels, from Alberta's oil sands to China's vast stores of coal, would have grave long-term consequences.

It says that the carbon released, if it continued to waft into the atmosphere as it does today, would drive up global temperatures between six and eight degrees and persist in the atmosphere for more than 1,800 years.

Climate models are not perfect and are less reliable the farther into the future they extend, but scientists say they are the only available means of exploring different scenarios.